Nonradiative energy transfer from perylene to Co2+ and Ni2+ ions has been investigated below the phase transition in small unilamellar vesicles. In the case of cobalt, the quenching of perylene fluorescence can be described well by long-range Foerster dipole-dipole energy transfer. Although fluorescence decay data for perylene quenched by nickel also fits the Foerster model, other evidence suggests a different quenching mechanism which is more akin to the shorter-range Dexter exchange interaction.